Radiation-induced parotid changes in oropharyngeal cancer patients: the role of early functional imaging and patient−/treatment-related factors

Abstract

BackgroundFunctional magnetic resonance imaging may provide several quantitative indices strictly related to distinctive tissue signatures with radiobiological relevance, such as tissue cellular density and vascular perfusion. The role of Intravoxel Incoherent Motion Diffusion Weighted Imaging (IVIM-DWI) and Dynamic Contrast-Enhanced (DCE) MRI in detecting/predicting radiation-induced volumetric changes of parotids both during and shortly after (chemo)radiotherapy of oropharyngeal squamous cell carcinoma (SCC) was explored.MethodsPatients with locally advanced oropharyngeal SCC were accrued within a prospective study offering both IVIM-DWI and DCE-MRI at baseline; IVIM-DWI was repeated at the 10th fraction of treatment. Apparent diffusion coefficient (ADC), tissue diffusion coefficient Dt, perfusion fraction f and perfusion-related diffusion coefficient D* were estimated both at baseline and during RT. Semi-quantitative and quantitative parameters, including the transfer constant Ktrans, were calculated from DCE-MRI. Parotids were contoured on T2-weighted images at baseline, 10th fraction and 8th weeks after treatment end and the percent change of parotid volume between baseline/10th fr (∆Vol10fr) and baseline/8th wk. (∆Volpost) computed.Correlations among volumetric changes and patient-, treatment- and imaging-related features were investigated at univariate analysis (Spearman’s Rho).ResultsEighty parotids (40 patients) were analyzed. Percent changes were 18.2 ± 10.7% and 31.3 ± 15.8% for ∆Vol10fr and ∆Volpost, respectively. Among baseline characteristics, ∆Vol10fr was correlated to body mass index, patient weight as well as the initial parotid volume. A weak correlation was present between parotid shrinkage after the first 2 weeks of treatment and dosimetric variables, while no association was found after radiotherapy. Percent changes of both ADC and Dt at the 10th fraction were also correlated to ∆Vol10fr. Significant relationships were found between ∆Volpost and baseline DCE-MRI parameters.ConclusionsBoth IVIM-DWI and DCE-MRI can help to detect/predict early (during treatment) and shortly after treatment completion the parotid shrinkage. They may contribute to clarify the correlations between volumetric changes of parotid glands and patient−/treatment-related variables by assessing individual microcapillary perfusion and tissue diffusivity.Electronic supplementary materialThe online version of this article (10.1186/s13014-018-1137-4) contains supplementary material, which is available to authorized users.

Repetitive MRI of organs at risk in head and neck cancer patients undergoing radiotherapy

“…No study so far included the sublingual glands. All patients in these studies received primary or postoperative, curatively-intended, radio(chemo)therapy with IMRT [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [26], [27], [28] or 3D-radiotherapy [25], [27], [28]. Radiation doses to the primary tumor ranged from 60 to 74 Gy.…”

Morphology, Volume, and Density Characteristics of the Parotid Glands before and after Chemoradiation Therapy in Patients with Head and Neck Tumors

“…We believe that volumetric changes are also related to a greater or lesser degree of tissue vascularization. Patients with more vascularized parotid glands have a greater volume reduction, possibly due to increased tissue oxygenation, which leads to higher radiosensitivity of the gland [21]. Moreover, the reduced volume of parotid glands might be due to acinar loss or fibrosis [19].…”

A novel bayesian approach with conditional autoregressive specification for intravoxel incoherent motion diffusion‐weighted MRI

“…For the diagnosis of head‐and‐neck (HN) cancer, it has been shown that the combined use of D and D ∗ can increase the diagnostic accuracy in predicting malignancy in HN masses with respect to the ADC . In addition, IVIM can also be useful to assess the effect of radiotherapy in normal tissues, since they are usually irradiated during the treatment …”

“…7,8 In addition, IVIM can also be useful to assess the effect of radiotherapy in normal tissues, since they are usually irradiated during the treatment. [9][10][11] The most reported approach for the estimation of D, D * and f in clinical research is a non-linear least square fitting of the IVIM signal on a voxel-wise basis, where the optimization algorithms classically employed are 13 and Trust Region 14,15 strategies. However, the goodness of fit of such a standard approach is strongly influenced by Signal-to-Noise Ratio (SNR) of the data, especially for the estimation of D * , making it difficult to assess small localized regions.…”